Control system for elevators



March 5, 1929. G, w, LAUTRUP ET AL 1,704,331

CONTROL SYSTEM FOR ELEVATORS .Filed Feb. ll 1926 2 Sheets-Sheet l 7 I /05 C/O 05 H//e w44 //5 musa Uy /72 @272 /04 im a www ATTORNEY March 5, 1929. G. .w. LAUTRUP ET A1.

.coNTRoL SYSTEM FOR ELEvAToRs 'Filed Feb. l, 1926 2 Sheets-Sheet @MX M C H }|NvENToR5 Patented Mar. 5, 1929.

UNITED STATES GEORGE W. LAUTRUP, 0F

KILL, NEW JERSEY, ASSIGNORS T0 OTIS ELEVATOR COMIANY,- OF JERSEY CITY,

NEW JERSEY, .A CORPORATION OF NEW JERSEY.

CONTROL SYSTEM FOR ELEVA'TORS.

Application tiled February The 'invention relates to control systems and particularly to control systems for elevators.

In elevator systems where power operated car gate and hatchway door mechanism is employed, or where the gate and door are manually operated, it is desirable to effect the .movement of the gate and door into open positions by the time that the car has stopped at the ioor. Such operation is advantageous particularly because of the amount of time which is saved. In high speed elevator systems, the time gained in making each stop is an important factor and, when the gain for a whole trip is considered, it may be seen that the operating' eiiiciency of the whole system is raised considerably. It is further in the interest of operating efficiency, where mechanism is employed to bring the car to a level with the desired landing in stopping, to cause the automat-ic gate and door operation to occur during the stopping period so as to cause the car gate and vhatchway door to be fully opened by the time that the car stops. Under the above conditions, the speed of the car might be accidentally increased during the gate and door opening operation or while the gate and door are open with a passenger in the lact of stepping into or out of the car.

In carrying out this invention, a direct current generator is employed to supply power to the elevator motor and the voltage of the generator to obtain full speed operation of the motor is varied by varying the current supplied to the ield winding of the generator from a source of relatively high voltage. As one feature of the invention, the field winding of the generator is supplied with current from a source of relatively low voltage to obtain the desired slow speedsfor the stopping operation and to insure that such slow speeds shall not be exceeded during the period when the hatchway door, and car gate when used, might be partially or wholly open.

Other features and advantages will become apparent from the following description and appended claims.

While the invention will be described, by way of illustration, as embodied in a system in which the car is under the control of an operator and in which self-leveling mechanism is provided to cause the car to be brought to a stop level With the landing, it is to be understood that the invention is also applicable vployed wherein the coils and contacts 1, 1926. Serial No. 85,232.

to other elevator systems, whether provided with self-leveling mechanism or not, such as those in which push button control is employed for causing only the stopping of the car at the landings or both the starting and stopping of the Qar or those in which the starting of the car is under the control of an operator while the slow down and stopping is automatic.

In the drawings:

Figure 1 is a diagram of an elevatorrcontrol system embodying the invention; and

Figure 2 is a schematic representation of the elevator car, showing the arrangement of the car switch and of mechanism suitable for effecting the leveling and car gate and hatchway door opening operations.

Referring to Figure 1, no attempt is made to show the coils and contacts of the various electromagnetic switches in their associated positions,a straight diagram being emof the various switches are separated in such manner as torender the circuits involved relatively simple. Also the parts of other switches and apparatus are separated in the interest of simplifying the diagram. For a clearer understanding of the invention, the stationary contacts of the swiches are illustrated in cross section.

The motor generator set comprises a driving motor 11, illustrated as of the alternating current type, and a variable voltage direct YONKERS, NEW YORK, .AND GEORGE N. CRABBE, 0F CRESS- current generator 12. The rotor of the driving motor is designa-ted lvand'its stator 14. The armature of the generator is designated 15, its series ield winding 16 and its separately excited field winding 17. The elevator motor is designated as a whole by the numeral 20, its armature being designated 21 and its field winding 22.- 250 is the main eX- citer for supplying current for the control circuits aswell as for the generator field winding during oar switch operation. The armature of this exciter is designated 251, its series field winding 252and its shunt iield winding 253. 254 is an auxiliary exciter for supplying current for the generator field winding during the leveling period. The armature of this exciter is designated 255, its series field winding 256 and its shunt field winding 257. These exciters also are driven by motor 11. In eases where a direct current source is available for the driving motor, the main exciter 250 may be omitted and this source used n heu thereof. An adjustable resistance 23 1s arranged in shunt to the generator series field winding. Discharge resistance 24 is pro- Lvided for the generator separately excited ing different conditions of operation. 30 is the release coil for the elevator motor electromagnetic brake. This vcoil is provided with discharge resistances 31, 32 and 33for controlling the application of the brake unv der differentconditions of operation. 34 and 35 are the up slow sp-eed contacts and the down slow speed contacts respectively of the leveling switch, the leveling switch up and down fast speed contacts being designated 36 and 37 respectively. 38 is the armature and 40 is the field winding of the motor 4l for moving therollers of the leveling switch into position to clear the leveling cams. 42 is the armature and 43 is the field winding of the door control motor 44.' 45 indicates the alternating current supply means for the driving motor.. 47 is a triple pole knife switch for connecting the driving motor to the mains. The car switch is designated as a whole by the numeral 48. 50 is the safety switch in the car. The series of door contacts are indicated by a single set of contacts 51. The gate contacts are indicated as 52. The various safety, limit, stop and emergency switches are omitted in order to simplify the description.

The electromagnetic switches have been designated as follows:

Afpotential switch,

B-up main direction switch,

C-down main direction switch,

D-irst accelerating switch,

E-Fsecond accelerating switch,

F-series field switch,

G-series field relay,

H-main brake and field switch,

J-door control motor switch,

K-door control motor maintaining relay,

yM*maintaining relay,

N-sequence relay,

O-accelerating relay,

P-hard brake switch,

LB-up leveling direction switch,

LC-down leveling direction switch,

LH-leveling brake andfeld switch,

LF-fast speed leveling relay.

Throughout the description which follows, these letters, in addition to the usual reference numerals, will beapplied to the parts of celerating switch cont-acts E 57, line the above enumerated switches. For example, contacts B 11-1 are contacts on the up main direction switch, while actuating coil A 53 is the coil that operates the potential switch. The electromagnetic switches are shown in their deenergized positions. Reactances are similarly designated by the character X..

Upon the closing of the knife switch 47, the driving motor l1 is energized and it starts in operation, bringing the generator l2 and exciters 250 and 254 up to full speed.A Starting means for the driving motor are omitted to simplify the description. The voltages of the exciters are thus brought up to their normal operating values and the elevator motor field winding 22 and potential switch actuating coil A 53, being connected to exciter 250, are energized.y It is to be noted that the circuit for coil A 53 is through safety switch 50, `/Vith the elevator motor at rest, the current supplied to its field winding 22 'is reduced by section 54 of resistance 29, providing what may be termed a standing field. The circuit for the elevator motor field winding may be traced from the left-hand or posi- 'tive (fr) terminal 18 of the main exciter 250, line 55, by way of line 56 .through field winding 22, resistance section 54 and second acright-hand or minus terminal 19 of eX- citer 250. It is not desired to apply full no1'- mal exciter voltage to the field winding 22 when the elevator motor is not in operation because of increased power consumption. On the other hand', it is not desired to have this field winding deenergized with the elevator motor at rest as a matter of safety and because of the time constant involved in building up. The potential switch, upon operation, causes the engagement of contacts A 60 and A 61, preparing the circuits from the main exciter 250 to the generator separately excited field winding, brake release coil 30 and the control circuits, and of contacts A 260 and A 261, preparing the circuits for connecting the auxiliary eX- citer to the generator field winding. The condition of the circuits so far described might be termed normal.

Referring brieiy to Figure 2, the car switch 48 comprises a set of up contacts 62, 63, 64, and 66 and a set of down contacts 67, 68, 69, A and 71. A contact segment 72 for bridging the contacts of each set is mounted on the segmental support 73 of insulating' material. A cam 74 is formed on the support above the pivot point 75. The cam is formed with a centrally disposed depression 7 6 into which the operating roller 77 of the. gate and door switch 78 extends with the car switch in neutral or off position. The switch 78 is pivoted at 80 so that movement of the car switch in either direction causes the engagement of the switch contacts. The car switch is operated by meansmof a control handle 81.

58, to the i the electromagnetic It is preferred to provide centering springs (not shown) on the car switch to cause it to be returned to oli' position when released by the operator.

Referring back to Figure 1, assume that the system is designed for an installation of several ioors and that the car is at rest at the first ioor with the gate and door open. In the starting operation, the operator first gives the car switch a slight initial movement to effect the closure ot the gate and door switch 78. For convenience of' description, this switch is arranged to complete a circuit for the door-control motor switch actuating coil J 82. This circuit may be traced from terminal 18, by way of line through contacts A 60, by way ol line 83 through coil J 82, resistance 84 and switch 78, line 85, switch 50, line 86, line 58, to terminal 19. The door control motor switch, upon operation, causes'the engagement ot contacts J 87, completing the circuit for tl e door control motor 44. This circuit may be traced from terminal 18, by way ot line through contacts A 60, by way ot line 88 through contacts- J 87, door control motor field winding 43 and armature 42, by way ol line 58 through contacts A 61, to terminal 19.

Referring again to Figure 2, motor 44 opcrates pneumatic gate and door operating mechanism, as for example through linkage 90 to move valve 91 for gate engine 92 to gate closed position and to withdraw the retiring cam 93 from engagement with the roller provided on the end of the door engine valve lever 94. The lever 94 is operated by a spring to move valve 95 for the door engine 96 to door closed position. The gate and door engines operate through mechanism not Ashown to close the car gate99 and hatehway door 109. It is to be understood that a door is provided in the hatchway at each landing.

Referring back to Figure 1, it the operator, after lie has closed the fate and door desires to open them, or if he desires to arrest their movement, he may do so by releasing the. car switch to return to offl position. This causes the opening ot the gate and door switch 78v with the consequent deenergization ot coil J 82 and the separation ol contacts J 87. In this manner, the circuit for the motor 44 is broken. The spring 97, shown in Figure 2, operates upon the deenergization oi motor 44 to move valve 91 and, through cam 93 and lever 94, valve 95 into positions to cause the reverse operations of the engines 92 and 96 to open the gate and door. Obviously other f'orms of power operated gate and door mechanisn'is, such as electric in lieu of pneumatic, may be employed without departing from the spirit of the present invention.

Assuming that the gate and doors -are closed, the gate contacts 52 and door contacts 51 are in engagement. The operator may nowI move the car switch to full operated position to start the car in the up direction. It is to be noted that the gate and door switch 78 remains in closed position so long as the car switch is moved out of neutral position. Upon the engagement of Contact segment 72 and contact 64, circuits are simultaneously completed for the oppositely wound coils N 98 and N 100 of the sequence relay, actuating coils H 101 of the main brake and field switch and B 102 of the up main direction switch being in the circuit for coil N 100. The engagement of the Contact segment and contacts 65 and 66 prepares circuits for the actuating coils of' the accelerating switches.

The circuit for coil N 98 of the sequence relay may he traced from terminal 18, by way of line 55 through contacts A 60, by way of line 108 through coil N 98 and resistance 104, contacts 62 and 64 of' the car switch, by way of line 105 through contacts C 106 of the down main direction switch, line 85, to terminal 19, as above traced. The circuit f'or coil N 100 may be traced from terminal 18, by way of line 55 through contacts A 60, by way of line 107 through door contacts 51, gate contacts 52. sequence relay contacts N 108, and coils N 100, H 101 and B 102, contacts 63 and 64 of the car switch, to terminal 19, as above traced. The purpose of the sequence relay N is to insure the closure of the gate and doors before starting the car. Coils N 98 and N 100, being differentially wound, oppose each other, when energized simultaneously, to prevent v the operation of the relay. If either coil is energized ahead of the other, or if either coil alone is energized, contacts N 108 separate, preventing the starting of the car. If either the gate contacts 52 or any of the door contacts 51 are separated atthe time that car switch segment 72 engages contacts 64, coil N 98 alone is energized, resulting in the separation of contacts N 108. The separation ot' contacts N 108 prevents the energization of' coil N 100, maintaining the sequence relay operated, and of' coil B 102, preventing the operation of the up main direction switch to effect the starting of the car. The gate and door switch 78, thereforeis closed by the initial movement of' the car switch so that the gate and door contacts may be closed before the engagement of segment 72 and 'contact 64. However, it' the car switch moved into position where segment 72 enga-ges contact 64 before the closure of the door and gate contacts, the sequence relay operates to prevent the starting of the car. Thus it. is impos sible to start the car on the door or gate con,- tacts.

Assuming that the sequence relay has operated, in order to start the car, the car switch is returned to a position with segment 72 disengaged from Contact, 64, deenergizing coil N 98 to permit eontactsN 108 to reengage. If

the gate and door are closed, the car switch" may be returned immediately to full on position. Otherwise, closing of the gate and door must be effected before the car switch is moved into full on position.

It is preferred to provide the main direction switches with a mechanical interlock to prevent their simultaneous operation. Such an interlock may be of the form of a walking beam pivotally mounted for engaging catches on the armatures of these switches. Upon operation of the up main direction switch in response to the energization ol its actuating coil B 102, contacts B 110 separate and contacts B 111, B 112 and B 113 engage. The separation of contacts B 1.10 breaks the circuit leading from the car switch down feed contact 69, contacts B 110 and the corresponding down direction switch contacts C 106 serving as electrical interlocls. The engagement of contacts B 113 prepares the circuit for the up main direction switch holding coil B 115 and the main brake and field switch holding coil H 116. The engagement of contacts B 111 and B 112 completes a circuit from the main exciter 250 to the generatorseparately excited field winding. This circuit may be traced from terminal 18, by way of line through contacts A 60, resistance 27 and contacts B 111, by way of line 117 through field winding 17, b y way of line 58 through contacts B 112 and contacts A 61, to terminal 19.

The main brake and field switch H operates simultaneously with the main direction switch B. Switch H, upon operation, causes the separation of contacts H 119, H 122 and H 123 and the .engagement of contacts H 124, H 125, H 126 and H 127. The separation of contacts H 119 disconnects the generator separately excited field winding from the generator armature. The purpose of this arrangement will be explained later. 'Contacts H 122 are in the circuit for connect-v..

ing the generator field Winding@ 17 tothe auxiliary exciter 254. The purpose of this arrangement also will be explained later. The separation of contacts H 123 disconnects resistance 33 from across the brake release coil 30. Resistance 33 being of low ohmic value, its disconnection before contacts H 124 engage prevents excess power consumption lfrom exciter 250.' The engagement of contacts H 127 establishes a circuit for the door Cil control motor maintaining relay actuating coil K 130. This circuit may be traced from terminal 18, by way of line 55 through contact-s A 60, by way of' line 83 through coil J 82, by way of line 131 through up leveling direction switch contacts LB 132` down leveling direction switch contacts lLC 133, contacts H 127 and coil K 130, line 85, to terminal 19, as previously traced. The engagement of contacts H 125 further prepares the circuits for the actuating coils 4of the acceleratingr switches. The engagement of contacts H 126 short-circuits section 54 of the elevator motor coil vK 130 in the circuit above traced is subject to the potential drop across resistance 84. T he system isarranged so that the voltage thus applied to coil K 130 is sufiicient to effect the operation of the relay. Contacts K A136 engage, upon the operation of the relay, to bypass contacts H 127. The purpose of this arrangement will be seen from later description.

rI'he brake release coil 30 being energized, the elevator motor field being connected directly to the main exciter 250 and current being supplied from the generator armature 15 to the elevator motor armature 21, due to the energization of the generator separately excited field winding, the elevator l motor starts.

As the brake releases, the brake switch contacts 135 separate to insert cooling resistance 137 in series with the brake release coil. These brake switch contacts are preferably arranged to be separated at the end of the releasing operation. Separation of contacts 135 also breaks the short circuit around coil O 138, permitting the operation of the accelerating relay O. This relay operates to cause the engagement of contacts O 140, completing the circuit for the first accelerating switch actuating coil D 141. The purpose of this arrangement is to utilize the time constant of the brake for timing the acceleration of themotor, more specifically, for timing the operation of the first accelerating switch. Although the brake release coil is energized at the same time that power-is supplied to the motor. the brake shoes do not lift at once because of the inherent time const-ant of the brake magnet and because the brake shoes and lever arms represent considerable mass to be set in motion. The circuit for coil'D 141 completed by contacts O 1 40 may be traced from terminal 18. by way of lineI 55 through contacts A 60, by way of line 107 through the door cont-acts 5l, gate contacts 52 and contacts N 108, by way of line 142 through contacts H 125. contacts O 140 and coil D 141, contacts 65 and 64 of the car switch, to terminal 19, as previously traced.

The operation of the first accelerating switch, in response to the cnergization of its actuating coil. causes the engagement of contacts D 143, D 144, D 145 and D 146. The

engagement of contacts D 143 completes the circuit I'or the leveling switch motor 41. This circuit may be traced from terminal 18, by way of line 55 through contacts A 60, by way of line 147 through contacts D 143, field winding 40 and armature 38 of motor 41, by way of line 58 through contacts A 61, to terminal 19. The leveling switch motor, upon energization, acts to move vthe leveling switch operating rollers so as to clear the leveling cams during movementof the car. This operation will be explained later. The engagement of contacts D 144 completes the circuit for holding coils B 115 and H 116. This circuit may be traced from terminal 18, by way of line 55 through contacts A 60, by way of line 148 through coil H 116 and contacts D 144, by way ot line 150 through coil B 115 and contacts B 113, line 151, line 85, to terminal 19, as previously traced. The purpose ot the energization of these holding coils will be seen from later description. The engagea ment of contacts D 146 completes the circuit for the second accelerating switch actuating coil E 152. This circuit may be traced from terminal 18, by way of line 55 through contacts A 60, by way of line 107 through door contacts 51, gatey contacts 52 and contacts N 108, by way of line 142-through contacts H 125, by way of line 153 through contacts D 146, reactance X 154 and coil E 152, car switch contacts 66 and 64, to terminal 19, as previously traced. The engagement of contacts D 145 short-circuits section 155 of re-` f sistance 27, increasing the voltage applied to the generator field winding. Thus the generator E. M. F. speed of the motor.

The second accelerating switch E does not operate immediately the circuit for its actuating coil is completed, its action being delayed by the effect of reactance X 154. Upon operation, contacts E. 156 and E 57l separate and contacts E 157 and E 158 engage, The separation of contacts E 156 removes the shunt circuit around a portion of resistance 160. The separation of contacts E 156 betore contacts E 158 engage prevents excess power consumption from exciter 250. The engagement of contacts E 158 completes the circuit tor the first accelerating switch holding coil D 161 and the maintaining relay actuating coil M 162. This circuit may be traced from terminal 18, by way of line 55 through contacts A 60, by way of line 151 through contacts E 158, reactance X 163, coil D 161 and coil M 162, line 85, to terminal 19, as previously traced. The maintaining relay contacts M 164 are thus caused to by-pass contacts D 144. The purpose of this arrangement will be described later. The engagement of contacts-E 157 short-circuits section 165 of resistance 27 to increase the voltage applied to the generator field winding. The E. M. F. of the generator, therefore, increases to its full value and the speed of the elevator motor increases. The separation of contacts `s increased, increasing the E 57 removes the short circuit for section 167 of resistance 29 in the elevator motor field winding circuit, bringing the elevator motor up to full speed.

The starting of the car in the down direction is accomplished in ay similar manner and will be only briefly described. The operator first moves the car switch into osit-ion to cause the closure of the gate an door and then into full on position where its contact segment 72 bridges contacts 67, 68, 69, 70 and 71. Thus the circuit is completed for the down main direction switch actuating coil C 168. This circuit may be traced from terminal 18, through coil H 101 as previously traced, by way of line 170 through coil C 168, car switch contacts 68 and 69, by way of line 171 through contacts B 110, line 85, to terminal 19, as previously traced. The circuit for coil N 98 is by way of line 172. The circuit for coil D 141 is by way of line 17 3. The circuit for coil E 152 is by way of line 174. The down main direction switch, upon operation, causes the separation of contacts C 106 and the engagement of contacts C 175, C 17 6 and C177, these contacts corresponding with up main direction switch contacts B 110, B 111,l B 112 and B 113 respectively. The holding coil of the down main direction switch is designated C 178. Further than this, the operation of starting the car in the down direction is the same as described for starting it in the up direction.

Assume that the car is running in the up direction and that the operator centers the car switch between the second and third floors in order to stop at the third floor landing. Thus the contact segment 72 moves off contacts 66, 65, 64 and 63 an'd the circuits for the second accelerating switch actuating coil E 152, iirst accelerating switch actuating coil D 141, main brake and field switch actuating coil H 101, up main direction switch actuating coil B 102 and sequence relay coils N 98 and N 100 are. broken. The second accelerating switch dropsout immediately. The lirst accelerating switch, main brake and ield switch and up main direction switch are maintained operated, however, by holding coils D 161, H 116 and B 115 respectively. The deenergization ot coils N 98 and N 100 is in preparation for the next starting operation. It is to be noted that switch 78 is opened by the centering of the car switch. The circuit for coil J 82. however, is maintained through contacts H 127 and K 136 in parallel and coil K 130.

The second accelerating switch, upon dropping out, causes the sepalaation of contacts E 157 and E 158 and the reengagement of contacts E 57 and E 156. The separation of contacts E 157 reinserts section 165 of resistance 27 in series with the generator separately excited ield winding to decrease the E. M. F.

of the generator. The engagement of coni tacts E 57 short-circuits section 167 of resistnecte'd to the leveling switch ance 29,y increasing the strength of the elevator motor field for thel stopping operation. Vith the generator E. M. F. lowered and the strength of the elevator motor ield increased, the speed of the elevator motor is decreased. The separation of contacts E 158 breaks the circuitffor holding coil D 161 and coil M 162. The first accelerating switch D and maintaining relay M do not drop out immediately, however, their action being delayed by the effect of reactance X 163in series with the coils and the discharge resistance 160 in parallel with the reac-tance and the coils. `The engagement ofcontacts E 156 to short-circuit a portion of resistance 160 is effective to prolong the time element of the switch and relay. The time element may be adjusted to the desired value by changing the amount of the resistance portion short-circuited. Relay M is preferably ladj usted to hold in at a smaller current value than the accelerating switch This may be readily accomplished due to the fact that the relay is much smaller and therefore lighter in construction than the accelerating switch and requires less current to hold in.

The first accelerating switch, upon dropping out, causes the separation of contacts D 143, D 144, D 145 and D 146. The separation of contacts D 144 is in preparation for the next starting operation, contacts M 164 remaining inA engagement to maintain holding coils H 116 and B 115 energized. The separation of contacts D 146 also is in preparation for the next starting operation, the circuit for coil E 152 having been broken by the movement of the car switch 'as above described. The separation of contacts D 145 removes the short circuit for section 155 of resistance 27, decreasing the strength of the generator field. Thus the generator E. M. F. is again decreased and the speed of the elevator motor `is reduced.

The separation of contacts D 143 dee-nergizes the leveling switch motor 41. -In this manner the operating rollers of the leveling switch are extended for engagement by the leveling cams. .Referring briefly to Figure 2, the leveling switch motor is operatively conby means of an arm 180 on the motor shaft` a connecting link 181 and a lever 182. In the starting operation, the motor 4 1 being energized, arm 180 rotates, acting through `link 181 and lever-182 to move the leveling switch as a whole about a pivot. In this manner the leveling switch operating rollers 183 and 184 are moved into position where they do not engage the leveling cams 185 and 186 during motion of the car, a stop being provided to determine the extent of the movement. It is to be understood that leveling cams. are provided for each fioor. The leveling switch is 187 secured to the car pivoted on a bracket frame. In theastopping operation, upon the deenergization of the leveling switch motor, a spring (not shown) moves the lever 182 and therefore the leveling switch back into the first described position with -the rollers 183 and 184 extended for engagement by the leveling cams. Each pair of leveling switch contacts 34, 35, 36 and 37 comprises a stationary contact and a movable contact operated by the engagement of its correspondingroller and levelingcam. The fast speed contacts 36 and 37 are arranged to separate before their corresponding slw speed contacts 34 and 35 in the leveling operation. Springs (not shown) are provided for causing the separation of the contacts of the pairs as the leveling operation is effected and stops are provided for determining the extent of movement of the rollers as they ride ofl" the leveling cams.

It will be assumed thatthe car has not reached the landing and that the. up leveling switch operating roller 183 moves onto the Vertical surface of up leveling cam 185 before relay M drops out. ing switch up slow speed contacts 34 completes a circuit for the up leveling direction switch actuating coil LB 188 and the leveling brake and field switch actuating coil LH 190. This circuit may be traced from terminal 18, by way of line 55 through contacts A 60, line 191, leveling switch contacts 34, by way of line 192 through vcoil LB 188 and coil L 190, line 85, to terminal 19, as previously traced.

he engagement of the leveling switch up fast speed contacts 36 completes the circuit for fast speed vleveling relay actuating coil LF 193. This circuit may be traced from ter- The engagement of levelminal 18, by way of line 55 through contacts L A560, line 191, leveling switch contacts 34, line 194, leveling switch contacts 36, by way of line 85 through coil LF 193, to terminal 19, as previously traced. It is to be noted that, due to the fact that the circuit for coil LF 193 is through leveling switch slow speed contacts 34, the circuit for coils LB 188 and LH 190 must be made inorder that the circuit for coil LF 193 may be completed. i

The up leveling direction switch LB, upon operation, causes the separation tof contacts LB 132 and the engagement of contacts LB 195, LB 196 and LB 197. Contacts LB 132 will be referred-to later. The engagement of contacts LB 195 and LB 196 further prepares the circuit for connecting the generator separately excited field winding to the auxiliary exciter 254. The engagement of contacts LB 197 completes the circuit for up series field relay actuating coil G `198 and up hard brake switch actuating coil P 200. This circuit may The leveling brake and field switch, operating simultaneously with the up leveling direction switch, causes the separa-tion of contacts LH 205, LH 206 and LH 212 and the engagement of contacts LH 207 and LH 208. Contacts LH 205 are in the circuit for resistance 33 across the brake release coil. Contacts LH 206 are in series with contacts H 119 in the circuit for connecting the generator separately excited field winding to the generator armature. `Contacts LH 207 by-pass contacts H 124 in the circuit for the brake release coil. Contacts LH 28() by-pass con- -tacts H 126 in the circuitfor section 54 of the motor field resistance 29. The purpose of contacts LH 205, LH 206, LH 207 and LH 208 will be seen as the description proceeds.l Contacts LH 212 break the shunt circuit comprising resistance 160 for coils D 161' and M 162.

The fast speed leveling relay, upon operation, causes the engagement ot contacts LF 213 and LF 214. The engagement of contacts LF 213 short-circuits resistance 28 employed t-o reduce the fiow of current through the generator field winding for slow speed operation during leveling. The engagement of contacts LF 214 by-passes switch 78, as well as contacts LB 132,LC 133,H 127 and K 136 and coil K 130 through resistance 84, in a circuit for 'coil J 82 ofthe door control motor switch.

Since the engagement of contacts LF 214 generally occurs substantially simultaneously with the separation of contacts LB 132, the switch J does not drop out. Even if switch J should drop out., the immediate reenergi- Zation oit' coil .l 82 upon the engagement of contacts LF 214 would prevent the operation of the gate and door operating mechanism due to the time required for the mechanism to start in operation. The circuit for the door control motor maintaining relay coil K 130, however, is broken by the separation of' contacts LB 132.

1 he separation of contacts LH 212 to break the circuit for resistance 160 as above set forth causes relay M to drop out and separate contacts M 164. As a result the circuit for holding coils B 115 and H 116 is broken. permitting the up main direction switch and main brake and field switch to drop out. Switch B,upon dropping out,causes the separation of contacts B 111, B 112 and B113 and the engagement of contacts B 110. The separation of contacts B 113 and the engagement of' contacts B 110 is in preparation for the next starting operation. The separation of contacts B 111 and B 112 disconnects the generator field winding from the main exciter 250.

.. However, the field winding is simultaneously connected to the auxiliary exciter by the engagement of contacts H 122 of the main brake and field switch as set forth below. The switch H, upon'dropping out, causes the separation of contacts H 124, H 125, H 126 and H 127 and the engagement of contacts H 119,

H 122 and H 123. The separationof contacts H -125 and H 127 in preparation for the next starting operation. The separation ot contacts H 124 and H 126 is without effect, the circuit for the brake release coil 30 being maintained by contacts LH 207 and section 54 of' resistance 29-remaining short-circuited by contacts LH 208. The engagement of' contacts H 119 and H 123 also is without effect as the circuit for-reconnecting the generator field winding to the generator armature is maintained broken by contactsLH 206 and the shunt circuit for the brake release coil 30 comprising resistance 33is maintained broken by contacts LH 205. The engagement ot' contacts H 122, however, completes the circuit for connecting the generator field winding` to the auxiliary exciter 254. This circuit may be traced from the left-hand or positive (-lterminal 262 of exciter 254, by way of line 263 through contacts A. 260, contacts LF 213, contacts H 122 and contacts LB 195, line 264, by way of line 117 through field winding 17, line 265, by way of line 266 through contacts LB 196, and contacts A 261, to the right hand or negative terminal- 267 of exciter 254. With the fieldv winding` so connected, an E. M. F. is generated which causes the elevator motor'to run at a suitable fast leveling speed.

Discharge resistance 24 acts not only to smooth out the changes in generator E. M. F. due to the reinsertion of resistance 27 in 4circuit with the generator field winding in steps but also acts to prevent a sudden drop in the value of the E. M. F. upon changing over from the main to the auxiliary exciter. It is to be understood that resistance 27 may be controlled in any number of steps, two being shown merely for convenience of description.

Relay G and switch P do not operate immediately their actuating coils are energized, their action being 4delayed by reactance X 203. Switch P, however, is adjusted to operate almost immediately and, upon operation, causes the separation of contacts P 221, disconnecting resista-nce 32 from across the brake release coil 30. Relay G, upon operation, causes the engagement of contacts G 222, completing the circuit for the series field switch actuating coil F 223; This circuit may be traced from terminal 18, by way of line 55 through contacts A 60, by way of line 224 through contacts G 222 and coil F 223, by way of line 58 through contacts A 61, to terminal 19. Switch F, upon operation, causesthe separation of contacts F 225, breaking the circuit including resistance 23 in shunt to the generator lseries field winding 16. The generator series field is so wound that, without the parallel resistance 23, it would have too great an eect for proper operation of the car.

The desired compounding is obtained by employing the low resistance shunt. Upon separation of contacts F 225, the strength of the series field is increased for the leveling operation so as to aid in bringing the motor to a stop. A certain strength of series field gives the best results in leveling and this strength is that which most nearly compensates for differences of load. However, were a field strength of such magnitude employed for full speed operation, its effect would be too great to give proper acceleration and retardation. The short delay in the action of relay G, and therefore switch F, upon the initiation of the leveling operation, is desirable in order that the current in the generator armature-elevator motor armature circuit may adjust itself to such a value that proper series field strength during the leveling operation may be obtained.

As the car nears the third flood landing, roller 193 rides of't' the vertical surface onto the oblique surface of cam 185. Thisresults in the separation of leveling switch up fast speed contacts 36, deenergizing fast speed leveling relay coil LF 193. Relay LF, upon dropping out, causes the separation of contacts LF 213 and LF 214. The separation of contacts LF 213 removes the short circuit for resistance 28. The generator E. M. F. is thus lowered and the elevator motor runs at its slow leveling speed. The separation of contacts LF 214 breaks the circuit for the door control motor switch coil J 82. Switch J, upon dropping out, causes the separation of contacts J 87 to deenergize thevmotor 44, thus effecting the automatic gate and door opening operation. The gate and door operating mechanism functions in the same manner as described for opening the gate and door in response to centering the car switch. In this manner the automatic gate and door l opening operation is timed so that the gate and door open as the car stops at the landing. It is to be noted, however, that the automatic gate and door opening operation cannot take plate until the leveling switch fast speed contacts separate.

Shortly before the car reaches the exact level with the landing, the roller 183 rides off the oblique surface ofcam 185, thereby sepas rating` the leveling switch up slow speed contacts 34. The circuit for coils LB 188 and LH 190 is thus broken. Switch LH drops out, causing the separation of contacts LH 207 and 'LH 208 and the reengagement of contacts LH 205', LH 206 and LH 212. The .engagement of contacts LH 212 is in preparation for the next starting operation. The separation of contacts LH 207 breaks the circuit for the brake release coil 30, effecting the application of the brake. The separation of contacts LH 207 also breaks the circuit for accelerating relay coil O 138. The accelerating relay O drops out, separating contacts 0140 in preparation for the next starting operation. The separation' of contacts LH 208 rei'nserts section' 54 of resistance 29 in se- 'tacts engage,

ries with the elevator motor field winding, reducing the current therein to a standing field value. The reengagemcnt of contacts LH 206 reconnects the generator field winding to the generator armature. The polarity of this connection is such that the generator sends current through the field winding in such manner as to oppose the flux which produces the generator E. M. F., thus tending to destroy the residual flux of the generator field. f

Up leveling-direction switch LB, dropping out simultaneously ,with switch LH. causes the separation of contacts LB 195, LB 196 and LB 197 and the engagement of contacts LB 132. The engagement of contacts LB 132 is in preparation for the next starting operation. The separation of contacts LB 195 and LB 196 disconnects the generator field vwinding from the auxiliary exciter, the winding being simultaneously connected to the generator armature as set forth-above. The separation of contacts LB 197 breaks the circuit for coils G 198 and P 200. The relay G drops out immediately but the dropping out of switch P is delayed slightly due to the effect of the reactance X 203 and discharge resistance 226. lt is to be noted that the discharge current folr` up coil P 200 and the reactance passes through down coil P 227 in such direction as to cause coil P 227 to assist coil P 200 infmaintaining switch P in operated condition. Relay G, upon dropping out, causes the separation of contacts G 222 to deenergize coil F 223, switch F dropping out in turn to cause the engagement of contacts F 225. The engagement of contacts F 225 reconnects resista-nce 23 in parallel `with the generator series eld winding 16. Switch P, upondropping out, causes the engagement of contacts P 221.

`Thus the brake being applied and the generator `separately excited field winding being disconnected from the exciters, the car is brought to rest level with the third floor landing. Since the engagement of contacts P 221 is delayed, the brake release coil 30 discharges only into resistance 31 of relatively high ohmic Value and a hard application of the brake is obtained. In this manner a positive stop at the landing is assured.

With the sequence of operations as above described the car will be slowed down and stopped level with the desired landing without sacrifice of smoothness. However, should the car switch be centered with the car at a greater distance from the landing, the maintaining relay would hold in to effect, through its -contacts M 164, the retention of the main direction switch and main brake and field switch in operated condition. Should relay M drop out before the leveling switch conthe subsequent engagement of the leveling switch contacts as the leveling switch roller rides onto the cam would cause circuit for the field windinor the auXiliary exciter.

the operation of switches LB and LH and relay LF to bring the car to a level with the floor. In the event that the car switch is centered late in the stopping operation, as for example when the leveling switch operating roller strikes the leveling cam upon the dropping out of the first accelerating switch D, the immediate separation of contacts LH 212 forces the dropping out of the main direction switch and the main brake and field switch to permit the immediate transfer of the fieldterminal 18, by way of line 55 through con-v tacts A 60, line 191, contacts 35, by way of line 230 through coil LC 228, by way of line 192 through coil LH 190, line 85, to terminal 19, as previously traced. Contacts LH 205, LH 206 and LH 212 are separated and contacts LH 207 and LH 208 are engaged so that the circuit tor resistance 33 across the brake release coil is broken, the generator separatelv excited field winding is disconnected from the generator armature, the bra-ke release coil is energized and resistance section 54 for the elevator motor field winding is short cir cuited. Contacts LH 212 insure the dropping out of the main` direction switch. The switch LC operates to cause the separation of contacts LC 133 and the engagement of contacts LC 231, LC 232 and LC 233. The separation of contacts LC 133 is without particular effect at this time.

The engagement of contacts LC 231 and LC 232 connects the generator field winding to Due to the reversal of the fiow of current through the generator field winding from that during the leveling operation with the car approaching the floor in the up direction, the car is caused to start in the down direction. Since relay `LF is :not operated, resistance 28 is included in the g, causing the motor to run at slow leveling speed.

The engagement of contacts LC 233 completed a'c'ircuit for the down series field relay actuating coil G 234 and the down hard brake switch actuating coil P 227. This circuit may be traced from terminal 18, by way of line 55 through contacts A 60, by way ofl line 235 through contacts LC 233, coil G 234, coil P 227 and portion 236 of reactance X 203, line 204, by way of line 58 through contacts A 61, to terminal 19. `Relay G and switch P do not operate immediately upon the engagement of contacts LC 233. When approaching the floor in the up direction, t-he current flowing through reactance portion 202 caused a fiuX to be built up in the reaetance X 203 in one direction. Upon the separation of contacts LB 197, the current in the reactance and coil P 200 discharged into resistance 226 tending to maintain the flux built up and, as previously explained, switch P in operated condition. Upon the engagement of contacts LC 233 on the overrun, the current supplied to coils Gr 234 and P 227 must reverse the flux in the reactance, thus taking a longer time to build up to a value sufficient to cause the operation of relay G and switch P. Thus contacts F 225, depending for their operation upon the operation of relay Gr, remain closed momentarily to insure that the current in the generator armature-motor armature circuit has fallen to a low value. Since the current in the series field winding may be fiowing in a direction such as to cause the generation of an E. M. F. which is of proper polarity for operating the car in the down direction, `immediate increase in the strength of the series field might result in an overrun in the down direction. As the car returns to the fioor, it is stopped by the separation of the leveling switch slow speed contacts 35 ina manner similar to that described for approaching the floor in -the up direction.

Ii the overrun is great enough to cause the engagement of the leveling switch down fast speed contacts 37 as well as the leveling switch down slow speed contacts 35, coil LF 193 is energized. As before, relay LF causes the engagement of contacts LF 213 te shortcircuit resistance 28. Thus the elevator Inotor is caused to run at its fast leveling speed. Relay LF also causes the engagement of contacts LF 214 to energize coil J 82 again in the event that it has become deenergized. Upon such an overrun, the automatic gate and door opening operation does not occur until contacts LF 214 separate, as previously described. Further than this, the operation on an overrun is as above described.

It is to be understood that the operator may control both the acceleration and retardation of the car by moving the car switch in steps. Should the operator suddenly move the car switch from one position into the other, for example from up into down position, injury to the system is prevented by contacts B 110 which remain separated until the up direction switch drops out. It is to be noted that, when the car is suddenly reversed or stopped between floors or stopped by opening the safety switch 50, the switch P is not operated. Thus contacts P 221 are in engagement and a soft application of the brake is obtained.

This arrangement for the control of the strength of' the generator field prevents an increase in speed of the elevator car above of the elevator motor during the stoppingperiod is controlled by means of resistance in series with the separately excited field winding of the generator which supplies power4 to the motor, there is always the possibility of all or a portion of such resistances becoming short-circuited or grounded, causing the speed of the elevator motor to increase. If mechanism were employed, as in the present system, to initiate the automatic opening of the gate and door before the car has been finally stopped at the landing, the sud-v den increase in speed might occur while the gate and door were being opened or after the gate and door were open. In the present system, the car cannot run at an excessive speed during the opening of the gate and door or while the gate and door are open. This will be apparent from the foregoing description of a self-leveling elevator system wherein, due to the fact that the circuitincluding resistance 27 for connecting the generator field winding to the main exciter is broken by the main direction switch contacts, the accidental short-circuiting of resistance 27 during the leveling operation cannot effect an increase in the speed of the elevator car. Also, connections for the leveling operation must be made in order to effect the automatic gate and door opening operation, since contacts on the leveling direction switches con- 'trol the circuit for the gate motor maintaining relay actuating coil K 130. By employing an auxiliary exciter o f relatively low voltage to supply current to the generator field winding, the maximum excitation of the generator field and consequently the generator E. M. F. and elevator motor speed during the leveling period are fixed. Thus an accidental short circuit of resistance 28 duri-ng the gate and door opening operation or while the gate and door are open can do no more than cause the elevator motor to run at its fast leveling speed.

As many changes could be made in'the above arrangement and many apparently widely different embodiments of this inven tion could be made without departing from the scope thereof, it is intended that all Inatter contained in the above description or shown .in the accompanying drawings shall be interpreted as illustrative and not kin a limiting sense. l

What is claimed is:

1. In combination; an elevator car; a

last named means Icomprising means for\ causing said winding fto be energized from said auxiliary source.

' 2. In combination;l an elevator car; a hoisting motor therefor; a generator for supplying current to said motor, said generator having a field winding; a main exciter; an auxiliary exciter of relatively lowvoltage; common means for driving said generator and exciters; means for causing said motor to run at a certain speed, said means comprising means for connecting said winding to the main exciter; and means forcausing said motor to run at a slower speed, said last named means comprising means for disconnecting said Winding from the main exciter and connecting it to the auxiliaryexciter.

l 3. In combination; an elevator car; a hoisting motor therefor; a generator for supplying current to said motor, said generator having a` field winding; a main source of current; means for causing the motor to op-l erate the car between landings, said means comprising means for causing said winding to be energlzed from said main source;

an auxiliary source of current of relatively i low voltage; and means for causing the motor to bring the car to a'stop at a desired landing, said last named means comprising means for causing the field winding to be energized from said auxiliary source.

4. In combination; an elevator car; a hoisting motor therefor; a generator for supplying current to said motor, said generator having a field winding; a main source of current; means for causing the motor to operate the car between landings, said means comprising means for causing said winding to be energized from said main source; an auxiliary source of current of relatively loa7 voltage; and means for causing the motor to energized from said main source; an auxiliary source of current of relatively low voltage; means for causing the motor to bring the car to a stop at a desired landing, said last named means comprising means for disconnecting said winding from the main. source and connecting it to said auxiliary source; a hatchway door; mechanism for caulsing the opening of said door; and means forinitiating the operation of said mechanism during the operation of the second named means.

6. In combination; an elevator car; a hoisting motor therefor; a generator for supplying current to said motor, said generator having a field winding; a main source of current; an auxiliary source of current of relatively low voltage; means forI causing said motor to run at a certain speed, said means comprising means for connecting said winding to the main source; a hatchway door; mechanism for causing the opening of said door; and means for preventing thek motor running above a slower speed than said certain speed during the opening of said door or while the door is open, said last car to a level with a desired landing in stopping at a slower speed than said certain speed, regardless of whether it underruns or overruns the landing, said second named means comprising means for disconnecting said lield winding from the main exciter and connecting it to the auxiliary exciter; a car gate; a hatchway door; mechanism for causing the opening of said gate and door; and means for initiating` the operation of said mechanism during the operation of the second named means.

8. In combination; an elevator car; a hoisting motor therefor; a generator for supplying current to said motor, said generator having a field winding; a main source of current; an auxiliary source of current; a resistance; means for connecting the main field winding to the main source in circuit with said resistance to cause the starting of the motor; means for short-circuiting said resistance to increase the speed of the motor; a hatchway door; mechanism for causing the opening of the door; and means for permitting the motor to runat a slower speedthan said certain speed but preventing an increase in speed above said slower speed in the event of the vshort-circuiting of said resistance from any cause during the operation of said mechanism, said last named means comprising means for disconnecting said Winding from said main source and connecting it to the auxiliary source.

9. In combination; an elevator car; a hoisting motor therefor; a generator for supplying current to said motor, said generator having a eld winding; a main exciter; an auxiliary exciter of relatively low voltage; common means for driving said generator and exciters; a resistance; means for starting thc motor, said means comprising means for connecting said winding to the main exc-iter and for thereafter short-circuiting said resistance to bring the motor up to full speed; means for causing the motor to bring the car to a level with a desired landing in stopping, regardless of whether it underruns or overruns the landing, said second named means comprising means for disconnecting Said winding from the main exciter and for connecting it to the auxiliary. exciter to cause the motor to run at a fast leveling speed, a second resistance, and means for causing the insertion of said second resistance in circuit with said winding and auxiliary exciter to cause the motor to run at a slow leveling speed; a car gate; a hatchway door; and means, responsive to the operation of said means for causing the insertion of said second resistance in circuit with said winding. and auxiliary exciter, for causing the opening of said gate and door.

, In testimony whereof, We have signed our names to this specification.

GEORGE W. LAUTRUP. GEORGE N. CRABBE. 

